One patient was killed and three others suffered slight injuries in a fire at Durham Regional Hospital in central North Carolina.

Hospital operations chief Katie Galbraith says no one else was hurt in the fire which was first reported as an explosion about 2:15 a.m. Tuesday on the hospital's sixth floor.

Galbraith says the hospital's sprinkler system worked properly and the fire was controlled as firefighters arrived. Other patients were moved to other parts of the hospital.

Galbraith says officials are still trying to determine exactly how the fire started.

Some patients were moved because of flooding caused by the sprinkler system. She says the three patients who were slightly injured had all been on ventilators before the blast and have been taken to the intensive care unit after being checked in the emergency room.

WRAL-TV in Raleigh-Durham reported that officials at the scene said the incident was first reported as an explosion, but they found no evidence of that.